"The European Physical Journal C"

Faraggi, Alon E.;Matone, Marco

doi: 10.1140/epjc/s10052-013-2694-1pmid: N/A

Abstract We show that if space is compact, then trajectories cannot be defined in the framework of the quantum Hamilton–Jacobi (HJ) equation. The starting point is the simple observation that when the energy is quantised it is not possible to make variations with respect to the energy, and the time parameterisation \(t-t_0=\partial _E{\mathcal {S}}_0\), implied by Jacobi’s theorem, which leads to the group velocity, is ill defined. It should be stressed that this follows directly from the quantum HJ equation without any axiomatic assumption concerning the standard formulation of quantum mechanics. This provides a stringent connection between the quantum HJ equation and the Copenhagen interpretation. Together with tunnelling and the energy quantisation theorem for confining potentials, formulated in the framework of quantum HJ equation, it leads to the main features of the axioms of quantum mechanics from a unique geometrical principle. Similar to the case of the classical HJ equation, this fixes its quantum analog by requiring that there exist point transformations, rather than canonical ones, leading to the trivial hamiltonian. This is equivalent to a basic cocycle condition on the states. Such a cocycle condition can be implemented on compact spaces, so that continuous energy spectra are allowed only as a limiting case. Remarkably, a compact space would also imply that the Dirac and von Neumann formulations of quantum mechanics essentially coincide. We suggest that there is a definition of time parameterisation leading to trajectories in the context of the quantum HJ equation having the probabilistic interpretation of the Copenhagen School.

Maltoni, Fabio;Mawatari, Kentarou;Zaro, Marco

doi: 10.1140/epjc/s10052-013-2710-5pmid: 25814870

Abstract Vector-boson fusion and associated production at the LHC can provide key information on the strength and structure of the Higgs couplings to the Standard Model particles. Using an effective field theory approach, we study the effects of next-to-leading order (NLO) QCD corrections matched to a parton shower on selected observables for various spin-0 hypotheses. We find that inclusion of NLO corrections is needed to reduce the theoretical uncertainties on the total rates as well as to reliably predict the shapes of the distributions. Our results are obtained in a fully automatic way via FeynRules and MadGraph5_aMC@NLO.

Alexandrou, Constantia;Constantinou, Martha;Dinter, Simon;Drach, Vincent;Jansen, Karl;Hadjiyiannakou, Kyriakos;Renner, Dru B.

doi: 10.1140/epjc/s10052-013-2692-3pmid: N/A

Abstract We present a stochastic method for the calculation of baryon three-point functions that is more versatile than the typically used sequential method. We analyze the scaling of the error of the stochastically evaluated three-point function with the lattice volume, and we found a favorable signal-to-noise ratio suggesting that our stochastic method can be used efficiently at large volumes to compute hadronic matrix elements.

Stetsko, M. M.

doi: 10.1140/epjc/s10052-013-2682-5pmid: N/A

Abstract Thermal radiation of electrically charged fermions from a rotating black hole with electric and magnetic charges in de Sitter space is considered. The tunneling probabilities for outgoing and incoming particles are obtained and the Hawking temperature is calculated. The relation for the classical action for the particles in the black hole’s background is also found.

Abdalla, M. C. B.;Carlesso, P. F.;Silva, J. M. Hoff da

doi: 10.1140/epjc/s10052-013-2709-ypmid: N/A

Abstract In this paper we consider a static domain wall inside a 3-brane. Different from the standard achievement obtained in General Relativity, the analysis performed here gives a consistency condition for the existence of static domain walls in a braneworld gravitational scenario. Also the behavior of the domain wall’s gravitational field in the newtonian limit is shown.

Morita, Kenji;Skokov, Vladimir;Friman, Bengt;Redlich, Krzysztof

doi: 10.1140/epjc/s10052-013-2706-1pmid: N/A

Abstract We discuss the properties of the net baryon number probability distribution near the chiral phase transition to explore the effect of critical fluctuations. Our studies are performed within Landau theory, where the coefficients of the polynomial potential are parametrized, so as to reproduce the mean-field (MF), the \(Z(2)\), and the \(O(4)\) scaling behaviors of the cumulants of the net baryon number. We show that in the critical region the structure of the probability distribution changes, depending on the values of the critical exponents. In the MF approach, as well as in the \(Z(2)\) universality class, the contribution of the singular part of the thermodynamic potential tends to broaden the distribution. By contrast, in the model with \(O(4)\) scaling, the contribution of the singular part results in a narrower net baryon number probability distribution with a wide tail.

Chopovsky, Alexey;Eingorn, Maxim;Zhuk, Alexander

doi: 10.1140/epjc/s10052-013-2700-7pmid: N/A

Abstract In this paper, we consider a system of gravitating bodies in Kaluza–Klein models with toroidal compactification of the extra dimensions. To simulate the astrophysical objects (e.g., our Sun and pulsars) with energy density much greater than the pressure, we assume that these bodies are pressureless in the external space, i.e., the space we inhabit. At the same time, they may have nonzero parameters \(\omega _{({\bar{\alpha }} -3)} \, ({\bar{\alpha }} =4,\ldots , D)\) in the equations of state in the extra dimensions. We construct the Lagrange function of this many-body system for any value of \(\Sigma =\sum _{{\bar{\alpha }}} \omega _{({\bar{\alpha }} -3)}\). Moreover, the gravitational tests (PPN parameters, perihelion and periastron advances) require a negligible deviation from the latent soliton value \(\Sigma =-(D-3)/2\). However, the presence of pressure/tension in the internal space results necessarily in the smearing of the gravitating masses over the internal space and in the absence of KK modes. This looks very unnatural from the point of view of quantum physics.

Davidović, Lj.;Nikolić, B.;Sazdović, B.

doi: 10.1140/epjc/s10052-014-2734-5pmid: N/A

Abstract We consider the closed string moving in a weakly curved background and its totally T-dualized background. Using T-duality transformation laws, we find the structure of the Poisson brackets in the T-dual space corresponding to the fundamental Poisson brackets in the original theory. From this structure we see that the commutative original theory is equivalent to the non-commutative T-dual theory, whose Poisson brackets are proportional to the background fluxes times winding and momentum numbers. The non-commutative theory of the present article is more nongeometrical than T-folds and in the case of three space-time dimensions corresponds to the nongeometric space-time with \(R\)-flux.

Dufour, G.;Debu, P.;Lambrecht, A.;Nesvizhevsky, V. V.;Reynaud, S.;Voronin, A. Yu.

doi: 10.1140/epjc/s10052-014-2731-8pmid: N/A

Abstract GBAR is a project aiming at measuring the free-fall acceleration of gravity for antimatter, namely antihydrogen atoms (\(\overline{\mathrm {H}}\)). The precision of this timing experiment depends crucially on the dispersion of initial vertical velocities of the atoms as well as on the reliable control of their distribution. We propose to use a new method for shaping the distribution of the vertical velocities of \(\overline{\mathrm {H}}\), which improves these factors simultaneously. The method is based on quantum reflection of elastically and specularly bouncing \(\overline{\mathrm {H}}\) with small initial vertical velocity on a bottom mirror disk, and absorption of atoms with large initial vertical velocities on a top rough disk. We estimate statistical and systematic uncertainties, and we show that the accuracy for measuring the free fall acceleration \(\overline{g}\) of \(\overline{\mathrm {H}}\) could be pushed below \(10^{-3}\) under realistic experimental conditions.

Chen, Deyou

doi: 10.1140/epjc/s10052-013-2687-0pmid: N/A

Abstract The standard Hawking formula predicts the complete evaporation of black holes. Taking into account the effects of quantum gravity, we investigate the tunneling of fermions from a five-dimensional rotating black string. The temperature is not only determined by the string, but also affected by the quantum numbers of the emitted fermion and the effect of the extra spatial dimension. The quantum correction slows down the increase of the temperature, which naturally leads to a remnant in the evaporation.